Microservices Architecture Patterns: Saga Distributed Transactions & Resilience4j Circuit Breakers

In distributed systems, traditional 2-Phase Commit (2PC) transactions fail to scale across independent databases. Learn how Orchestration and Choreography-based Saga patterns maintain eventual consistency with compensating transactions.

1. Resilience4j Circuit Breaker in Spring Boot 3

@Service
public class PaymentGatewayClient {

    @CircuitBreaker(name = "paymentService", fallbackMethod = "paymentFallback")
    @Retry(name = "paymentService")
    public PaymentResponse processPayment(PaymentRequest request) {
        return restTemplate.postForObject("/payments", request, PaymentResponse.class);
    }

    public PaymentResponse paymentFallback(PaymentRequest request, Throwable t) {
        log.warn("Payment service unavailable! Triggering graceful fallback. Cause: {}", t.getMessage());
        return new PaymentResponse("PENDING_RETRY", "Payment queued for offline batch processing.");
    }
}